[R-390] R-290a modified IF sub-chassis

[Gary I. Biasini]

Thanks to all who have responded.  I have now had the opportunity to trace
the circuit.  It appears to be  a partial implementation of the Capt. Paul
H. Lee product detector modification.  Referring to the R-390a 2K manual
description (Chapter 11, pages 31 following):

 

1.       There are no modifications to the panel wiring, so , steps 3 - 13
are not performed;

2.       Steps 15 and 16 appear to have been performed;

3.       Step 17 is 10K resistor not 11K;

4.       Steps 18 to 20 appear to have been performed;

5.       Step 21 was not performed;

6.       Step 22 appears to have been performed;

7.       Steps 23 and 24 are not performed presumably per suggestion of
Eugene A. Hubbell, W7DI;

8.       Step 25 appears to have been performed;

9.       Step 26 is a 1,000 uF 25VDC electrolytic rather than 63VDC as
prescribed;

10.   Instead of an insulated standoff per step 27, pin 4 of RT510 was used;

11.   Step 28 is a 27K resistor;

12.   Steps 29 and 30 are not performed;

13.   Step 33 (replacement tube 6BE6) is installed;

 

The link below is my rendition of the schematic including the mystery 8 pin
part previously advised of.  Again, any suggestion as to what this
modification accomplishes would be appreciated.

 

https://1drv.ms/b/s!AhXaYQRsUlJ0gbZ66H5Xvz8I_og_2A

 

73, Gary

 

From: Roy Morgan [mailto:k1lky68 at gmail.com] 
Sent: Tuesday, September 26, 2017 3:26 PM
To: Gary I. Biasini <gary.biasini at shaw.ca>
Cc: r-390 at mailman.qth.net
Subject: Re: [R-390] R-290a modified IF sub-chassis

 

 

On Sep 3, 2017, at 8:17 PM, Gary I. Biasini <gary.biasini at shaw.ca
<mailto:gary.biasini at shaw.ca> > wrote: 


The URLs to pictures of the modified module are below:

https://1drv.ms/i/s!AhXaYQRsUlJ0gbU1YrERkfud0axItQ

https://1drv.ms/i/s!AhXaYQRsUlJ0gbU5K1--TAXeKe4ZgQ

 

Gary,

 

That thing with the 8 leads MIGHT be an SSB module.  Or perhaps a diode quad
product detector.

 

Just guessing.  Never saw any such as that.

 

 

Roy